Core B is the Histopathology Core. This facility, located in the Strang Cancer Prevention laboratories at Rockefeller University, has efficiently served investigators of the NYCCSG (New York Colon Cancer Study Group) for nearly 10 years, providing fundamental data that has led to many high-quality publications and funded grants. The Principal Investigator is Martin Lipkin, and daily operation is supervised by K. Yang. The Core has developed rigorous, standardized protocols for animal dissection, tumor evaluation, tissue fixation, storage and distribution, and biomarker studies. This laboratory also has extensive experience with histopathological analysis of biopsies from subjects in clinical projects. In the last 3 years, we have added a second facility at the Montefiore Medical Center/Albert Einstein Cancer Center, supervised by WC Yang (who trained with K Yang) under the general direction of Augenlicht, to carry out additional assays such as Real-Time PCR, laser capture microdissection and fractionation of cells to represent the crypt-villous gradient of function. These two units have functioned well together, and both are thoroughly integrated into the conduct of the experiments to be carried out in the projects. Work by the two units is coordinated by discussion at our monthly meetings, and by almost daily communication between participants, especially Augenlicht and Lipkin, who have been collaborators for 25 years.